It's not up to data or metadata to ensure consistency and avoid corruption by themselves.
If that data's backend storage is a database, it's up to database.
If it's a filesystem, it's up to that filesystem.
Hence, on UNIX, stuff you're talking about depends on filesystem implementation. /etc is less "safer" than Windows Registry if it lies on ext2, and far more "safer" than it if it lies on properly configured ZFS.
Other than that, your post stands correctly.